Regulation of the beta- and delta-hemoglobin genes. A family with hereditary persistent fetal hemoglobin and beta-thalassemia.

We have studied a 41-year-old black male with the simultaneous occurrence of hereditary persistence of fetal hemoglobin (HPFH) and beta-thalassemia, and his two postadolescent sons, each heterozygous for one of the traits. The son heterozygous for beta-thalassemia had an elevated Hb A2, but the index case did not. The data from this pedigree indicate that the delta-allele trans to the beta-thalassemia gene was reponsible for the increased delta-chain production. Evidence from other cases of combination HPFH and beta-thalassemia indicates that regulation of the beta- and delta-chain production in beta-thalassemia is heterogeneous with respect to mechanism.